The preferred embodiment relates to magnetic resonance (MR) imaging, and more particularly to studies requiring real-time synchronization between the imaging data and external devices that are part of the study.
Functional MRI studies (fMRI) have moved into regular clinical usage. The basis of the fMRI experiment is to measure and localize the activity in the brain in response to external stimuli or during the performance of certain mental and physical tasks. In addition to providing academic information, these techniques also allow the mapping of certain brain centers in the diagnosis of disease and in pre-surgical planning. As the usage of these techniques has expanded, so has the range of their application. New applications include a patient population which may not be able to perform tasks on a predetermined timescale, forcing the fMRI system to adapt its stimulus presentation to a time course dictated by the patient.
Dynamic imaging studies involving patient motion during the scan have also become more commonplace in diagnostic imaging. A real-time indicator of cycle time or phase during an imaging study has value in later analysis and validation of the data.
Current time-stamps attributed to MR images depend on the scanner, hardware, pulse sequence, and reconstruction scheme used in the acquisition. These values are typically stored in the header of the MR image and are available to an external system once the final images are in a form in which they can be exported. The disadvantage of this technique is that in order to provide time-stamp information in a consistent manner, software at both the pulse sequence and image reconstruction stages must be modified to place the desired timing information in an accessible region of the image header. The ability to modify the software, synchronize with the clocks of the various scanner processors, and get the information in a usable form can be very invasive tasks, especially if multiple pulse sequences are utilized in the experiment.